Aberrations in the epidermal growth factor receptor gene in 958 patients with diverse advanced tumors: implications for therapy

p85β alters response to EGFR inhibitor in ovarian cancer through p38 MAPK-mediated regulation of DNA repair

EGFR signaling promotes ovarian cancer tumorigenesis, and high EGFR expression correlates with poor prognosis. However, EGFR inhibitors alone have demonstrated limited clinical benefit for ovarian cancer patients, owing partly to tumor resistance and the lack of predictive biomarkers. Cotargeting EGFR and the PI3K pathway has been previously shown to yield synergistic antitumor effects in ovarian cancer. Therefore, we reasoned that PI3K may affect cellular response to EGFR inhibition. In this study, we revealed PI3K isoform-specific effects on the sensitivity of ovarian cancer cells to the EGFR inhibitor erlotinib. Gene silencing of PIK3CA (p110α) and PIK3CB (p110β) rendered cells more susceptible to erlotinib. In contrast, low expression of PIK3R2 (p85β) was associated with erlotinib resistance. Depletion of PIK3R2, but not PIK3CA or PIK3CB, led to increased DNA damage and reduced level of the nonhomologous end joining DNA repair protein BRD4. Intriguingly, these defects in DNA repair were reversed upon erlotinib treatment, which caused activation and nuclear import of p38 MAPK to promote DNA repair with increased protein levels of 53BP1 and BRD4 and foci formation of 53BP1. Remarkably, inhibition of p38 MAPK or BRD4 re-sensitized PIK3R2-depleted cells to erlotinib. Collectively, these data suggest that p38 MAPK activation and the subsequent DNA repair serve as a resistance mechanism to EGFR inhibitor. Combined inhibition of EGFR and p38 MAPK or DNA repair may maximize the therapeutic potential of EGFR inhibitor in ovarian cancer.

ErBb Family Proteins in Cholangiocarcinoma and Clinical Implications

The erythroblastic leukemia viral oncogene homolog (ErBb) family consists of the receptor tyrosine kinases (RTK) epidermal growth factor receptor (EGFR; also called ERBB1), ERBB2, ERBB3, and ERBB4. This family is closely associated with the progression of cholangiocarcinoma (CC) through the regulation of cellular networks, which are enhanced during tumorigenesis, metastasis, and chemoresistance. Additionally, the constitutive activation of cellular signaling by the overexpression and somatic mutation-mediated alterations conferred by the ErBb family on cholangiocarcinoma and other cancers enhances tumor aggressiveness and chemoresistance by contributing to the tumor microenvironment. This review summarizes the recent findings on the molecular functions of the ErBb family and their mutations during the progression of cholangiocarcinoma. It also discusses the developments and applications of various devising strategies for targeting the ErBb family through different inhibitors in various stages of clinical trials, which are essential for improving targeted clinical therapies.

The combination of bevacizumab/Avastin and erlotinib/Tarceva is relevant for the treatment of metastatic renal cell carcinoma: the role of a synonymous mutation of the EGFR receptor

Metastatic clear cell renal cell carcinomas (mRCC) over-express the vascular endothelial growth factor (VEGF). Hence, the anti-VEGF antibody bevacizumab/Avastin (BVZ) combined with interferon alpha (IFN) was approved for the treatment of mRCC. However, approval was lost in July 2016 due to the absence of sustained efficacy. We previously showed that BVZ accelerates tumor growth in experimental models of mRCC in mice, results in part explained by down-regulation of the phospho tyrosine phosphatase receptor kappa (PTPRκ) in tumor cells. The epidermal growth factor receptor (EGFR) is a direct target of PTPRκ. Its down-regulation leads to constitutive activation of EGFR, an observation which prompted us to test the effect of the EGFR inhibitor erlotinib/Tarceva (ERLO) in addition to BVZ/IFN. The influence of the long non-coding RNA, EGFR-AS1, on ERLO efficacy was also addressed.

Methods: The effect of BVZ/IFN/ERLO was tested on the growth of experimental tumors in nude mice. The presence of germline mutation in the EGFR was evaluated on cell lines and primary RCC cells. In vitro translation and transfections of expression vectors coding the wild-type or the EGFR mutated gene in HEK-293 cells were used to test the role of EGFR mutation of the ERLO efficacy. Correlation between EGFR/EGFR-AS1 expression and survival was analyzed with an online available data base (TCGA).

Results: Tumor growth was strongly reduced by the triple combination BVZ/IFN/ERLO and linked to reduced levels of pro-angiogenic/pro-inflammatory cytokines of the ELR+CXCL family and to subsequent inhibition of vascularization, a decreased number of lymphatic vessels and polarization of macrophages towards the M1 phenotype. Cells isolated from surgical resection of human tumors presented a range of sensitivity to ERLO depending on the presence of a newly detected mutation in the EGFR and to the presence of EGFR-AS1.

Conclusions: Our results point-out that the BVZ/IFN/ERLO combination deserves testing for the treatment of mRCC that have a specific mutation in the EGFR.

Characterization of epidermal growth factor receptor (EGFR) P848L, an unusual EGFR variant present in lung cancer patients, in a murine Ba/F3 model

Lung cancer patients with mutations in epidermal growth factor receptor (EGFR) benefit from treatments targeting tyrosine kinase inhibitors (TKIs). However, both intrinsic and acquired resistance of tumors to TKIs are common, and EGFR variants have been identified that are resistant to multiple TKIs. In the present study, we characterized selected EGFR variants previously observed in lung cancer patients and expressed in a murine bone marrow pro-B Ba/F3 cell model. Among these EGFR variants, we report that an exon 20 deletion/insertion mutation S768insVGH is resistant to erlotinib (a first-generation TKI), but sensitive to osimertinib (a third-generation TKI). We also characterized a rare exon 21 germline variant, EGFR P848L, which transformed Ba/F3 cells and conferred resistance to multiple EGFR-targeting TKIs. Our analysis revealed that P848L (a) does not bind erlotinib; (b) is turned over less rapidly than L858R (a common tumor-derived EGFR mutation); (c) is not autophosphorylated at Tyr 1045 [the major docking site for Cbl proto-oncogene (c-Cbl) binding]; and (d) does not bind c-Cbl. Using viability assays including 300 clinically relevant targeted compounds, we observed that Ba/F3 cells transduced with EGFR P848L, S768insVGH, or L858R have very different drug-sensitivity profiles. In particular, EGFR P848L, but not L858R or S768insVGH, was sensitive to multiple Janus kinase 1/2 inhibitors. In contrast, cells driven by L858R, but not by P848L, were sensitive to multikinase MAPK/extracellular-signal-regulated kinase (ERK) kinase and ERK inhibitors including EGFR-specific TKIs. These observations suggest that continued investigation of rare TKI-resistant EGFR variants is warranted to identify optimal treatments for cancer.

Revisiting Epidermal Growth Factor Receptor (EGFR) Amplification as a Target for Anti-EGFR Therapy: Analysis of Cell-Free Circulating Tumor DNA in Patients With Advanced Malignancies

Purpose

To date, evidence for tissue epidermal growth factor receptor (EGFR) overexpression as a biomarker for anti-EGFR therapies has been weak. We investigated the genomic landscape of EGFR amplification in blood-derived cell-free tumor DNA (cfDNA) across diverse cancers and the role of anti-EGFR therapies in achieving response.

Methods

We assessed EGFR amplification status among 28,584 patients with malignancies evaluated by clinical-grade next-generation sequencing (NGS) of blood-derived cfDNA (54- to 73-gene panel). Furthermore, we curated the clinical characteristics of 1,434 patients at the University of California San Diego who had cfDNA testing by this NGS test.

Results

Overall, EGFR amplification was detected in cfDNA from 8.5% of patients (2,423 of 28,584), most commonly in colorectal (16.3% [458 of 2,807]), non–small-cell lung (9.0% [1,096 of 12,197]), and genitourinary cancers (8.1% [170 of 2,104]). Most patients had genomic coalterations (96.9% [95 of 98]), frequently involving genes affecting other tyrosine kinases (72.4% [71 of 98]), mitogen-activated protein kinase cascades (56.1% [55 of 98]), cell-cycle–associated signals (52.0% [51 of 98]), and the phosphoinositide 3-kinase pathway (35.7% [35 of 98]). EGFR amplification emerged in serial cfDNA after various anticancer therapies (n = 6), including checkpoint inhibitors (n = 4), suggesting a possible role for these amplifications in acquired resistance. Nine evaluable patients with EGFR amplification were treated with anti-EGFR–based regimens; five (55.6%) achieved partial responses, including three patients whose tissue NGS lacked EGFR amplification.

Conclusion

EGFR amplification was detected in cfDNA among 8.5% of 28,584 diverse cancers. Most patients had coexisting alterations. Responses were observed in five of nine patients who received EGFR inhibitors. Incorporating EGFR inhibitors into the treatment regimens of patients harboring EGFR amplification in cfDNA merits additional study.

Erlotinib for coexisting typical bronchial carcinoid and advanced lung adenocarcinoma: does the epidermal growth factor receptor mutation status matter?

Adenocarcinoma (AC) is the most common type of primary pulmonary malignancy. Lung carcinoid, however, is a rare neuroendocrine tumor. Their coexistence is extremely uncommon. We report the unique case of synchronous advanced lung AC of the right upper lobe (stage IIIB) and typical endobronchial carcinoid tumor in the contralateral lower lobe in a 49-year-old white female who had never smoked. PET-computed tomography scan revealed a fluorine-18-fluorodeoxyglucose-avid AC lesion, whereas the carcinoid tumor was fluorine-18-fluorodeoxyglucose occult. After two lines of platinum-based combination chemotherapies and radiotherapy, the AC progressed, and oral tyrosine kinase inhibitor therapy with erlotinib was initiated in third line. On erlotinib, the AC remained stable for 50 months until disease progression, whereas the carcinoid completely regressed. Molecular testing of the rebronchoscopied AC revealed an exon 19 deletion mutation in the epidermal growth factor receptor (EGFR) gene, whereas the carcinoid was retrospectively EGFR mutation negative. The patient eventually succumbed to ileus caused by intra-abdominal spread of disease, surviving a remarkable 80 months with good performance status throughout most of the follow-up period. To the best of our knowledge, this is the first reported case of synchronous primary lung cancers with different EGFR mutation status, describing an unexpected response of an EGFR-wild-type carcinoid to third-line erlotinib.

Overcoming resistance of targeted EGFR monotherapy by inhibition of STAT3 escape pathway in soft tissue sarcoma

Although epidermal growth factor receptor (EGFR) is often over-expressed in soft tissue sarcoma (STS), a phase II trial using an EGFR inhibitor gefitinib showed a low response rate. This study identified a new secondary resistance mechanism of gefitinib in STS, and developed new strategies to improve the effectiveness of EGFR inhibition particularly by blocking the STAT3 pathway.

We demonstrated that seven STS cell lines of diverse histological origin showed resistance to gefitinib despite blockade of phosphorylated EGFR (pEGFR) and downstream signal transducers (pAKT and pERK) in PI3K/AKT and RAS/ERK pathways. Gefitinib exposure was not associated with decrease in the ratio of pSTAT3/pSTAT1. The relative STAT3 abundance and activation may be responsible for the drug resistance. We therefore hypothesized that the addition of a STAT3 inhibitor could overcome the STAT3 escape pathway.

We found that the addition of STAT3 inhibitor S3I-201 to gefitinib achieved synergistic anti-proliferative and pro-apoptotic effects in all three STS cell lines examined. This was confirmed in a fibrosarcoma xenografted mouse model, where the tumours from the combination group (418mm³) were significantly smaller than those from untreated (1032mm³) or single drug (912 and 798mm³) groups.

Our findings may have clinical implications for optimising EGFR-targeted therapy in STS.

Significance of Phosphorylated Epidermal Growth Factor Receptor and Its Signal Transducers in Human Soft Tissue Sarcoma

Previous studies have shown that total epidermal growth factor receptor (EGFR) protein is highly expressed in soft tissue sarcoma (STS). We aimed to investigate the significance of phosphorylated-EGFR (pEGFR) and its activated-downstream signal transducers in STS tissue samples. A tissue microarray comprising 87 STS samples was assessed for total EGFR, pEGFR and its phosphorylated signal transducers and expression was correlated with clinicopathlogical parameters including patient outcome. Although the expression of total EGFR was significantly associated with adverse STS histologic grade (p = 0.004) and clinical stage (p = 0.012) similar to pEGFR, phosphorylated protein kinase B (pAkt) and phosphorylated extracellular signal regulated kinase (pERK), it is not a prognostic factor for survival. By contrast, the expression of pEGFR is an independent factor for cancer specific survival, while pERK is an independent prognostic factor for both overall and cancer specific survival in STS (p < 0.05, Cox proportional hazard model and log-rank test) in addition to the recognised factors of tumour grade and clinical stage. pERK and pEGFR are new independent prognostic factors for overall and/or cancer specific survival in STS. The expression of EGFR/pEGFR, and their associated downstream signal transducers, was associated with STS progression, suggesting that EGFR downstream signalling pathways may jointly support STS cell survival.

Sample types applied for molecular diagnosis of therapeutic management of advanced non-small cell lung cancer in the precision medicine

In this era of precision medicine, molecular biology is becoming increasingly significant for the diagnosis and therapeutic management of non-small cell lung cancer. The specimen as the primary element of the whole testing flow is particularly important for maintaining the accuracy of gene alteration testing. Presently, the main sample types applied in routine diagnosis are tissue and cytology biopsies. Liquid biopsies are considered as the most promising alternatives when tissue and cytology samples are not available. Each sample type possesses its own strengths and weaknesses, pertaining to the disparity of sampling, preparation and preservation procedures, the heterogeneity of inter- or intratumors, the tumor cellularity (percentage and number of tumor cells) of specimens, etc., and none of them can individually be a “one size to fit all”. Therefore, in this review, we summarized the strengths and weaknesses of different sample types that are widely used in clinical practice, offered solutions to reduce the negative impact of the samples and proposed an optimized strategy for choice of samples during the entire diagnostic course. We hope to provide valuable information to laboratories for choosing optimal clinical specimens to achieve comprehensive functional genomic landscapes and formulate individually tailored treatment plans for NSCLC patients that are in advanced stages.

Cyclin-dependent kinase pathway aberrations in diverse malignancies: clinical and molecular characteristics

Aberrations in the cyclin-dependent kinase (CDK) pathways that regulate the cell cycle restriction point contribute to genomic instability and tumor proliferation, and can be targeted by recently developed CDK inhibitors. We therefore investigated the clinical correlates of CDK4/6 and CDKN2A/B abnormalities in diverse malignancies. Patients with various cancers who underwent molecular profiling by targeted next generation sequencing (Foundation Medicine; 182 or 236 cancer-related genes) were reviewed. Of 347 patients analyzed, 79 (22.8%) had aberrant CDK 4/6 or CDKN2A/B. Only TP53 mutations occurred more frequently than those in CDK elements. Aberrations were most frequent in glioblastomas (21/26 patients; 81%) and least frequent in colorectal cancers (0/26 patients). Aberrant CDK elements were independently associated with EGFR and ARID1A gene abnormalities (P < 0.0001 and p = 0.01; multivariate analysis). CDK aberrations were associated with poor overall survival (univariate analysis; HR[95% CI] = 2.09 [1.35–4.70]; p = 0.004). In multivariate analysis, PTEN and TP53 aberrations were independently associated with poorer survival (HR = 4.83 and 1.92; P < 0.0001 and p = 0.01); CDK aberrations showed a trend toward worse survival (HR = 1.67; p = 0.09). There was also a trend toward worse progression-free survival (PFS) with platinum-containing regimens in patients with abnormal CDK elements (3.5 versus 5.0 months, p = 0.13). In conclusion, aberrations in the CDK pathway were some of the most common in cancer and independently associated with EGFR and ARID1A alterations. Patients with abnormal CDK pathway genes showed a trend toward poorer survival, as well as worse PFS on platinum-containing regimens. Further investigation of the prognostic and predictive impact of CDK alterations across cancers is warranted.

Obstructive jaundice caused by intraductal metastasis of lung adenocarcinoma

Obstructive jaundice caused by metastases to the porta hepatis is often observed in patients with various advanced cancers; however, metastasis of lung cancer to the common bile duct with subsequent development of jaundice is rare. A 75-year-old female with lung adenocarcinoma harboring epidermal growth factor receptor (EGFR) mutation (15-bp in-frame deletion in exon 19 and T790M in exon 20) developed obstructive jaundice during therapy. Obstruction of the common bile duct caused by an intraductal tumor was identified by computed tomography, endoscopic retrograde cholangiopancreatography, and endoscopic ultrasonography. Although primary cholangiocarcinoma was highly suspected according to the imaging findings, immunohistochemical evaluation of the intraductal tumor demonstrated thyroid transcription factor-1 positive adenocarcinoma. Furthermore, peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp analysis showed that the tumor contained the same EGFR mutation as that in the primary lung cancer. Thus, we confirmed intraductal metastasis from a lung adenocarcinoma. To our knowledge, this is the second report of obstructive jaundice caused by intraductal metastasis of lung cancer.

New and emerging treatment options for biliary tract cancer

Biliary tract cancer (BTC) is a group of relatively rare tumors with a poor prognosis. The current standard of care consists of doublet chemotherapy (platinum plus gemcitabine); however, even with cytotoxic therapy, the median overall survival is less than 1 year. The genetic basis of BTC is now more clearly understood, allowing for the investigation of targeted therapy. Combinations of doublet chemotherapy with antiepidermal growth factor receptor agents have provided modest results in Phase II and Phase III setting, and responses with small molecule inhibitors are limited. Moving forward as we continue to characterize the genetic hallmarks of BTC, a stepwise, strategic, and cooperative approach will allow us to make progress when developing new treatments.